Britain's economic growth is set to pick up in coming months and outstrip that of the United States, Japan and Germany, according to forecasts today from the Organisation for Economic Co-operation and Development (OECD) that come as a boost to Gordon Brown's government ahead of the election.

The Paris-based thinktank revised down its previous view on Britain's first quarter annualised growth to 2% from 2.4%, but that pace still beats its forecasts for Japan and Germany.

In the second quarter of this year, the OECD sees UK growth picking up to 3.1%, outpacing the United States, and all other countries in the G7 group of large economies apart from Canada.

Official data for the UK's first-quarter GDP growth is due out on 23 April. Most economists expect a quarterly growth rate to match the 0.4% expansion in the final three months of 2009, when the UK emerged from its deepest and most prolonged recession in decades. Signs, including more upbeat business surveys, that the recovery could pick up pace in the coming months has already boosted Labour in opinion polls.

One such survey on the dominant services sector today showed businesses were more optimistic and hiring new staff for the first time in almost two years.

While overall service-sector growth eased in March as new business came in at a slower pace following February's post-snow jump, activity was still very much in growth territory, according to the latest monthly poll of purchasing managers by Markit and the Chartered Institute of Purchasing and Supply.

Echoing other surveys suggesting a double-dip recession was avoided at the start of this year despite harsh weather, the main purchasing managers' index (PMI) number slipped to 56.5 from a three-year high of 58.4 in February. The number was below City economists' forecasts for a softer drop to 58 but was significantly above the 50-mark that separates growth from contraction. The reading was still seen by most analysts as pointing to overall economic growth in the first quarter although they also said it highlighted the fragility of the nascent recovery.

Paul Smith, senior economist at the PMI compiler Markit, said: "The UK recovery remains on track, with the service sector posting a pace of expansion consistent with those seen at the end of 2009. Over the first quarter, the headline index has averaged a reading broadly unchanged since Q4 [fourth quarter], pointing to a decent contribution from the services economy to Q1 GDP numbers.

"With positive manufacturing and construction PMI data indicating that recovery is increasingly broad-based, Q1 economic growth should at the very least match Q4's pace," he added, looking ahead to official GDP data due out on 23 April.

The PMI survey showed services companies – which in this survey include businesses such as hotels and restaurants but not retailers – were feeling more confident, with the business expectations number the strongest since last September.

The OECD is expecting growth across the G7 to pick up pace in the second quarter. It predicts combined GDP will rise 1.9% in the first quarter – a slightly faster pace than the 1.5% it had previously pencilled in but way below 3.7% in the fourth quarter. In the second quarter it is expecting 2.3% growth.

But the thinktank was keen to stress a number of pressures on the global recovery, including the winding down of some fiscal stimulus measures and continued weakness in consumer demand as unemployment remains high.

Despite some encouraging signs on activity, the fragility of the recovery, a frail labour market and possible headwinds coming from financial markets underscore the need for caution in the removal of policy support," said the OECD's chief economist, Pier Carlo Padoan.